1. Field of the Invention
In general, the present invention is related to devices that are used to hold expansion joints in place as concrete is poured. More particularly, the present invention relates to devices that help anchor and protect the expansion joints after the poured concrete has hardened.
2. Prior Art Description
When concrete is poured as pavement on streets, sidewalks and driveways, the concrete is rarely poured as a single form. Rather, the concrete is poured into smaller sections. The various smaller sections are divided by expansion joints. Concrete, like many other materials, expands and contracts in response to changes in temperature and humidity. Furthermore, the earth under a poured concrete surface may settle over time. The use of expansion joints enables different segments of concrete slab to settle in different degrees. The use of expansion joints, therefore, enables a concrete slab to compensate for stresses without cracking, thereby significantly increasing the useful life of the concrete slab.
There are many different types of expansion joints that have been used between adjacent concrete slabs. Some expansion joints are merely a wide open groove. However, such grooves fill with dirt and debris and soon harbor weeds and other plants. Furthermore, the roots of the growing plants can cause damage to the poured concrete, thereby greatly reducing the span of its functional life. To prevent plant growth, expansion joints are most often formed using a filler strip. The filler strip fills the expansion joint and prevents dirt and debris from gathering in the expansion joint.
Filler strips for concrete expansion joints are made from a material that is far softer than concrete. In this manner, when the concrete expands and contracts, the filler strip can absorb the forces without cracking the concrete. Filler strips are often just planks of wood. However, synthetic filler strips are also commercially available.
Wood plank filler strips are popular because they are widely available, come in a variety of precut sizes and are inexpensive. Furthermore, wooden plank filler strips can also be used to form an edge during the pouring of concrete. Consequently, a contractor can box off an area of concrete with wooden planks, pour the concrete into the form, and then leave the wooden planks in place as expansion joints.
The problem with wooden plank filler strips is that they tend to rot over time. The expansion joint, therefore, decomposes allowing weeds to take root in the expansion joint. In an attempt to prolong the life of an expansion joint, a contractor may use a synthetic filler strip. Synthetic filler strips tend to be far more flexible than planks of wood. Accordingly, if a synthetic filler strip is used, it cannot be used as a form edge unless it is strongly reinforced. The application of a synthetic expansion joint, therefore, can be far more labor intensive than a comparable wooden filler strip.
To assist in the application of both wooden filler strips and synthetic filler strips, anchoring systems have been developed that are designed to hold the filler strips in place as concrete is poured. In this manner, less labor is involved in reinforcing the filler strips prior to the pouring of concrete. Such prior art anchoring systems typically support the filler strip from the bottom of the filler strip. In this manner, the anchoring system becomes completely submersed by the poured concrete and cannot be seen. Such bottom support prior art anchoring systems are exemplified by U.S. Pat. No. 4,198,176 to Bentz, entitled Concrete Expansion Joint Forming Structure; U.S. Pat. No. 4,875,801 to Montrym, entitled Expansion Joint Brace And Aligner; and U.S. Pat. No. 4,936,704 to Killmeyer, entitled Expansion Joint Filler Strip Holder.
Bottom support anchoring systems are typically expensive and are difficult to cut to specific lengths. Furthermore, since the anchoring system engages the filler strip at the bottom of the filler strip, the anchoring system provides no support to the top of the filler strip. Lastly, such bottom support anchoring systems fail to provide any physical protection to the top of the filler strip that is exposed to the elements.
A need therefore exists for an anchoring system for an expansion joint filler strip that is low-cost, easy to adjust, and wherein the anchoring system both supports and protects the top of the filler strip. This need is met by the present invention as described and claimed below.